Study shows lack of interest in sex successfully treated by exposure to bright light

Media Release: European College of Neuropsychopharmacology (ECNP)
“For the science and treatment of disorders of the brain”

Study shows lack of interest in sex successfully treated by exposure to bright light

Embargo until: Monday 19th September, 00.01 CET (Vienna)

Exposure to bright light increases testosterone levels and leads to greater sexual satisfaction in men with low sexual desire. These are the results of a pilot randomised placebo-controlled trial, presented at the ECNP conference in Vienna.
Low sexual desire affects significant numbers of men after the age of 40, with studies finding that up to 25% of men report problems*, depending on age and other factors. Scientists had previously noted that sexual interest varies according to the seasons, prompting the idea that levels of ambient light may contribute to sexual desire.
Now a group of scientists from the University of Siena in Italy have tested sexual and physiological responses to bright light. They found that regular, early-morning, use of a light box – similar to those used to combat Seasonal Affective Disorder - led both to increased testosterone levels and greater reported levels of sexual satisfaction.
The scientists, led by Professor Andrea Fagiolini, took recruited 38 men who had been attending the Urology Department of the University of Siena following a diagnosis of hypoactive sexual desire disorder or sexual arousal disorder – both conditions which are characterised by a lack of interest in sex. Each man underwent an initial evaluation to determine the baseline level of interest in sex, with testosterone levels also being measured.
The researchers then divided the men into two groups. One group received regular treatment with a specially adapted light box, the control (placebo) group was treated via a light box which had been adapted to give out significantly less light. Both groups were treated early in the morning, with treatment lasting half an hour per day. After two weeks of treatment or placebo, the researchers retested sexual satisfaction and testosterone levels.
Professor Fagiolini said
“We found fairly significant differences between those who received the active light treatment, and the controls. Before treatment, both groups averaged a sexual satisfaction score of around 2 out of 10, but after treatment the group exposed to the bright light was scoring sexual satisfaction scores of around 6.3 – a more than 3-fold increase on the scale we used. In contrast, the control group only showed an average score of around 2.7 after treatment”.
The researchers also found that testosterone levels increased in men who had been given active light treatment. The average testosterone levels in the control group showed no significant change over the course of the treatment – it was around 2.3 ng/ml at both the beginning and the end of the experiment. However, the group given active treatment showed an increase from around 2.1 ng/ml to 3.6 ng/ml after two weeks.
Professor Fagiolini explained:
“The increased levels of testosterone explain the greater reported sexual satisfaction. In the Northern hemisphere, the body’s Testosterone production naturally declines from November through April, and then rises steadily through the spring and summer with a peak in October. You see the effect of this in reproductive rates, with the month of June showing the highest rate of conception. The use of the light box really mimics what nature does.
We believe that there may be several explanations to explain the underlying mechanism. For instance, light therapy inhibits the pineal gland in the centre of the brain and this may allow the production of more testosterone, and there are probably other hormonal effects. We’re not yet at the stage where we can recommend this as a clinical treatment. Even at that stage, there will be a few patients – for example those with an eye condition or anyone taking medicines which affect light sensitivity (some antidepressants, and some antibiotics, for example) – who would need to take special care. However if this treatment can be shown to work in a larger study, then light therapy may offer a way forward. It’s a small study, so for the moment we need to treat it with appropriate caution”.
The researchers note that there are several possible reasons for lack of sexual desire. Treatment depends on the underlying cause, but current therapeutic options include testosterone injections, antidepressants, and other medications. The researchers believe that light therapy may offer the benefits of medication, but with fewer side effects.

Commenting, Professor Eduard Vieta (Chair of the Department of Psychiatry and Psychology at the University of Barcelona Hospital Clinic and treasurer of the ECNP) said:

“Light therapy has been used successfully in the past to treat some forms of depression and this study suggests now that it may also work to treat low sexual desire in men. The mechanism of action appears to be related to the increase of testosterone levels. Before this kind of treatment, which is likely to be better tolerated than pharmacological therapy, gets ready for its routine use, there are many steps to be implemented, including replication of the results in a larger, independent study, and verifying whether the results are long-lasting and not just short-term”.

*See Epidemiology of Male Sexual Dysfunction, Konstantinos Hatzimouratidis, American Journal of Men’s Health / Vol. 1, No. 2, June 2007. The prevalence varies significantly according to the surveys reviewed in this paper.

Contacts, abstract, funding information, and other details are listed in ‘Notes’.

Notes for editors
Please mention the European College of Neuropsychopharmacology Congress in any stories which result from this press release.

Professor Andrea Fagiolini
Professor Eduard Vieta
ECNP Press Officer, Tom Parkhill tel +39 349 238 8191 (Italy)

The European College of Neuropsychopharmacology (ECNP)
The ECNP is an independent scientific association dedicated to the science and treatment of disorders of the brain. It is the largest non-institutional supporter of applied and translational neuroscience research and education in Europe. Website:
The annual ECNP Congress takes place from 17th to 20th September in Vienna. It is Europe’s premier scientific meeting for disease-oriented brain research, annually attracting between 5,000 and 8,000 neuroscientists, psychiatrists, neurologists and psychologists from around the world. Congress website:

Abstract; P.4.b.010 Light therapy as a treatment for sexual dysfunction; focus on testosterone levels (Monday 19th Sept, 12.15-13.45)
D. Koukouna, L. Bossini, I. Casolaro, C. Caterini,A. Fagiolini.
University of Siena, Department of Molecular Medicine, Siena, Italy. University of Siena Medical Centre - Azienda Ospedaliera Universitaria Senese - Department of Mental Health

Seasonality has shown to have a significant influence on sexual function and the pineal gland plays a key role in the neuroendocrine control of sexual activity. The retinohypothalamic tract carries information on the cycles light/dark to the suprachiasmatic nucleus of the hypothalamus that projects to the pineal gland and inhibits the production of melatonin [1]. When these impulses stop (at night, when light no longer stimulates the hypothalamus), pineal inhibition ceases and melatonin is released. Melatonin increases the secretion of prolactin, which contributes to sexual dysfunction. We aimed at demostrating that inhibition of the pineal gland activity through a light treatment may favorably affect sexual function reducing plasma levels of melatonin. We recruited a sample of 38 male subjects among outpatients referred to the Urology Department of the University of Siena on the basis of a diagnosis of primary hypoactive sexual desire disorder (HSDD) and sexual arousal disorder (SAD). Participants were randomly assigned to active light treatment (ALT) or placebo light treatment (L-PBO) and assessed before and after 2 weeks of treatment ALT/L-PBO via the Structured Clinical Interview for DSM-IV sexual disorders (SCID-d) and self-administered rating scale of the level of sexual satisfaction (1 to 10); testosterone levels were also assessed at baseline and after two weeks of treatment through blood samples. The ALT consisted of daily exposure to a white fluorescent light box (Super-Lite 3S), fitted with an ultraviolet filter and rated at 10,000 lx at a distance of 1 meter from screen to cornea for 30 min as soon as possible after awakening, between 7.00 a.m. and 8.00 a.m. The L-PBO was an identical light box fitted with a neutral density gel filter to reduce light exposure to 100 lx. The Mann–Whitney test for nonparametric data has been applied to analyze the differences between the ALT and L-PBO group at the time of recruitment and after 2 weeks of therapy. At baseline the two groups were clinically comparable; results after 2 weeks of therapy showed a significant improvement in sexual satisfaction in the group treated with ALT approximately 3 times higher than the group that received the placebo (p < 0.05), while no significant improvement was observed in the group L-PBO. Testosterone levels (range 2.7–10.9 ng/ml) at baseline were 2.1±1.3 ng/ml in ALT and 2.3±0.6 ng/ml in L-PBO group; after two weeks they raised at 3.6±1.1 ng/ml in ALT group (p < 0.05) while no significant difference emerged in L-PBO group. Our results suggest that the level of sexual satisfaction at baseline was roughly comparable in the two groups, with no statistically significant differences. After 2 weeks of treatment the group that received ALT showed a significant improvement in sexual function with respect to baseline level, about 3 times higher than the group that received L-PBO. This difference could also be attributed to increased levels of testosterone in subjects treated with active light therapy.

[1] Bossini, L., Caterini, C., Koukouna, D., Casolaro, I., Roggi, M., Di Volo, S., Fargnoli, F., Ponchietti, R., Benbow, J., Fagiolini, A., 2013. Light therapy as a treatment for sexual dysfunctions – beyond a pilot study. Psychiatr Pol 47(6), 1113–1122. [2] Bossini, L., Fagiolini, A., Valdagno, M., Roggi, M., Tallis, V., Trovarelli, S., Ponchietti, R., Castrogiovanni, P., 2009. Light therapy as a treatment for sexual dysfunctions. Psychother Psychosom 78(2), 127–128.
Funding: Institutional funds, University of Siena, Italy